For a variety of reasons, electrical utilities are routinely and frequently required to connect and disconnect service at subscriber locations. For example, a utility may need to disconnect service when a subscriber moves out of a particular location and then later reconnect service to the same location when another subscriber moves in. Likewise, utility companies are sometimes forced to disconnect service to a subscriber who does not pay, and then reconnect service when the subscriber's account is settled. There may be other reasons for disconnecting service at a subscriber location as well, such as to enable maintenance or repair.
A number of electricity metering devices currently exist that provide connect/disconnect capability through the use of a control relay, commonly referred to as a disconnect switch, internal to the meter. Electricity meters also often incorporate auxiliary control relays that can be operated to connect/disconnect particular types of devices, such as electric water heaters or other equipment.
In the past, disconnect switches at the electricity meter were operated manually. Today, however, utilities are able to operate service disconnect switches and auxiliary control relays remotely. For example, in a system in which electricity meters communicate with a utility control station via a wired or wireless network, the disconnect switch and/or auxiliary control relays in a meter can be controlled by transmitting a command or request via the network to the meter, which responds by opening or closing the disconnect switch or other control relay as requested. Alternatively, commands or requests to open or close a disconnect switch or other control relay may be received from a hand-held programming unit. Some hand-held programming units are designed to communicate with the meter via an optical port interface on the meter, whereas others are designed to communicate with the meter via the meter's wireless communications circuitry. Such commands or requests may also be received from other devices or sources via an option board that may be installed in the meter.
Regardless of the source of a remote request or command to open or close a disconnect switch or other control relay, there may be times when doing so would create unsafe or undesired conditions at the electricity meter. For example, if a disconnect switch or other control relay has been opened for some reason and a technician has been dispatched to the subscriber location, an unexpected closure of the switch or other control relay may result in harm to the technician. An unexpected interruption of service as a result of opening a disconnect switch or other control relay could also be problematic for certain residents, such as the elderly or those undergoing medical treatment, particularly when medical equipment must remain powered. In all such cases, safety is a significant concern.